The majority watches X-rated movies to satisfy a “fringe fantasy,” according to his research, and it would be unfair to extrapolate from that that it leads to criminal behaviour.

A handful of universities permitted him to address their campuses, and after appealing to some 2,000 mostly women students to take part, 20 heterosexual men agreed to discuss their sex lives in depth.

His first discovery: all the respondents watched adult videos online. Singles viewed twice the amount of pornography as others with an average of three 42-minute sessions weekly, versus 1.7 27-minute sessions for those in a committed relationship.

Second: almost all searched alone for online erotica, whether in a committed relationship or not. Respondents explained they just did not feel comfortable sharing such moments with others, even with a spouse or girlfriend.

According to his research, said Lajeunesse, men search out pornography that relates to their earliest sexual fantasies, generally conceived at age 12 at the onset of puberty. They are not looking for new tricks to show off.

Lajeunesse also dismissed suggestions that avid pornography enthusiasts seek to imitate in life what they see on screens, or that they watch X-rated videos in an attempt to purge vile sexual impulses.